1. Field of the Invention
The present invention relates to coatings and coating compositions and more particularly to coating compositions for use on plastics and other low conductivity substrates and to methods for their application.
2. Brief Description of the Prior Art
The use of parts formed from sheet molding compound (SMC) and other plastics in automobile bodies presents a number of advantages such as light weight and resistance to corrosion. One problem with the use of such parts, however, is that they are more difficult than metal to electrostatically spray paint. This difficulty is at least in part attributable to the fact that static electricity which develops as a result of the use of electrostatic spraying equipment can not be easily dissipated through the nonconductive parts. In order to solve this problem and impart conductivity to such parts it has been the practice to initially paint the parts with a primer which is rendered conductive by means of relatively large amounts of conductive carbon black in its composition. Such primers, however, have a resultant disadvantage in that they tend to be black or very dark gray in color. It may, therefore, be difficult to obtain good finishing coat hiding of the primer color.